The present invention relates to devices for boresighting firearms, and more particularly to such devices and methods utilizing light beams.
A wide variety of boresighting devices have been developed to facilitate proper alignment of the firearm scope or sight with the firearm bore. One such device includes a cartridge-shaped housing which fits within the chamber of the firearm. The housing includes a peephole at its rear end and a cross hair at its forward end such that one can look through the peephole and cross hair structure to precisely align the firearm bore with a target. The scope can then be adjusted as necessary to also bring the scope into a desired alignment with the target. An example of this device is seen in U.S. Pat. No. 2,773,309, entitled BORESIGHTING DEVICE FOR FIREARMS, issued Dec. 11, 1956, to Elliott. However, the housing, when slightly misaligned within the chamber, will create relatively large errors in the alignment of the bore with the target. Alignment of the scope under these conditions will not properly boresight the firearm.
Another device includes a light emitting device housed within a cartridge-shaped housing, which fits within the firearm chamber. The light emitting device directs a beam of light through the firearm bore and onto a target so that the bore can be aligned with the target. The scope is then also aligned with the target using either visual sighting or a second light emitting device on the scope. An example of this system is illustrated in U.S. Pat. No. 3,782,832, entitled METHOD OF BORESIGHT ALIGNMENT OF A WEAPON, issued Jan. 1, 1974, to Hacskaylo. However, as with the previously described device, slight misalignment of the housing within the chamber will cause relatively large errors in the alignment of the bore with the target.
Other boresighting devices have been developed and are typically mounted in the muzzle end of the firearm barrel. Examples of these devices are illustrated in U.S. Pat. No. 4,168,429, entitled INFRARED BORESCOPE DEVICE AND METHOD OF BORESIGHT ALIGNMENT OF A WEAPON, issued Sept. 18, 1979, to Lough; U.S. Pat. No. 3,787,693, entitled BORESIGHT ALIGNMENT DEVICE, issued Jan. 22, 1974, to Stone; and U.S. Pat. No. 2,711,204, entitled OPTICAL SIGHT ALIGNER, issued Jan. 16, 1973, to Steck.